Devices with critical dimensions on the order of 65 nanometers or less have involved integration of copper conductors and low-k dielectrics. Such devices require alternating material deposition processes and planarization processes. Following almost each step in the fabrication process, e.g., a planarization step, a trenching step, or an etching step, cleaning processes are required to remove residues of the plasma etch, oxidizer, abrasive, metal or other liquids or particles remaining which contaminate the surface of the copper wafer. Fabrication of the current advanced generation of devices require copper conductors and low-k dielectric materials (typically carbon-silica or porous silica materials), both of which can react with and be damaged by various classes of prior art removers.
Low-k dielectrics in particular may be damaged in the cleaning process as evidenced by etching, changes in porosity/size, and ultimately changes in dielectric properties. A continuous wet process is required to remove the residues without any effect on damaged low-k layer, for instance k-value shift and CD loss. In addition, copper surface control is considered to be important for reliable electrical properties: oxide layer on copper surface (CuOx) is required to be removed in the wet process, and re-oxidation on the bare copper surface needs to be prevented.
The conventional cleaning compositions comprising a fluorine-containing component, solvent, and water are known. And the conventional cleaning or development compositions having a basic pH, and being comprised of tetramethylammonium hydroxide, boric acid and water are also known.
1) Japanese patent laying open no. 2003-122028, to Kenji et al., describes a composition comprising 0.5% to 10% of a fluorine compound, greater than 30% of a mixed amide/ether solvent and water, and teaches that at solvent concentrations less than 30% corrosion of the wiring material becomes intense.
2) Japanese patent laying open no. 2001-5200, to Yoko et al., describes a resist removing composition for substrates comprising aluminum wiring, the composition comprising 0.1% to 2% ammonium fluoride, 20% to 98.8% of a polar organic solvent, 0.05% to 1.9% ascorbic acid, and 1% to 79.8% water, with pH less than 5.0. The listed polar organic solvents are N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, ethylene glycol, and propylene glycol.
3) U.S. Pat. No. 5,792,274, to Tanabe et al., describes a remover solution composition for resist which comprises (a) 0.2% to 8% a salt of hydrofluoric acid with a metal-free base, (b) 30% to 90% of a water-soluble organic solvent such as a glycol ether, and (c) water and optionally (d) an anticorrosive, at a pH of 5 to 8.
4) U.S. Pat. No. 5,939,336 describes residue remover compositions of ammonium fluoride, propylene glycol, ammonia and water, at a pH of from 7 to 8.
5) U.S. Pat. No. 5,972,862 describes a post-etch residue remover having: (A) 0.1% to 15% of a fluorine-containing compound such as hydrofluoric acid or ammonium fluoride; (B) 1% to 80% of a polar organic solvent selected from a list including amides, lactones, alcohols, alkyl acetates, alkyl lactates, alkylene glycols, glycol ethers, and sulfoxides; (C) 0.01% to 5% of an phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, or an organic acid; and (D) 1% to 50% of a quaternary ammonium salt. Water is not a specified component of the remover, and while there is no range specified for water, one example was described as containing 45.9% water. Examples show 1-10% NH4F, 0.1-1% organic acid, and 35-69% amide solvent, and presumably a balance (−P30% to 60%) water.
6) U.S. Pat. No. 5,792,274 describes a resist/residue remover having 0.2% to 8% of a salt of metal-free base and HF, 30% to 90% of a water-soluble organic solvent, and water where the pH is 5-8. The preferred solvents are ethylene glycol or ethylene glycol and dimethylsulfoxide.
7) U.S. Pat. No. 6,235,693 describes residue removers comprising 0.01% to 10% of fluorine compounds, 20% to 50% water, 20% to 80% of a piperidone and from 0 to 50% of an organic sulfoxide or glycol solvent, said composition having a pH between about 6 and about 10.
8) U.S. Pat. No. 6,468,951 describes a composition to remove silica residue from a borophosphosilicate semiconductor wafer, said composition having a basic or an acidic pH, and being comprised of: water; 0.01% to 95% of hydroxyl-functional solvent such as ethylene glycol or an alcohol; aqueous hydrofluoric acid; a tetraalkylammonium hydroxide; and about 0.001 wt % to about 10 wt % of a surfactant.
9) U.S. Pat. No. 6,638,899 describes a photoresist remover comprising hydrofluoric acid, a base free from metal ions, 30% to 80% of a water-soluble organic, water, and an alkali, wherein the pH of the remover is 8.5 to 10.
10) JP 3255551 describes a composition having 0.5-40% HF, 40-99.5% water, water-soluble organic solvent, and 0.5-40% anticorrosion agent, useful for removing resist in short time at low temperatures.
11) U.S. published Application No. 2004/010653 1, the disclosure of which is incorporated herein by reference thereto specifically for the semiconductor fabrication processes which form various types residue, each type of which can be removed with compositions of the present invention. This application discloses removers useful for copper/low-k material substrates, the removers comprising a metal-free salt of hydrogen fluoride; 50% to 98% of a water-soluble organic solvent; an acid; and water.
12) U.S. published Application No. 2005/006713 describes a composition to remove photoresist and Sacrificial Antireflective Coating (SAC), said composition having a basic pH, and comprising an alkaline or alkaline earth metal base, a quaternary ammonium hydroxide, oxidizer and a passivation agent. This application discloses that the concentration of quaternary ammonium hydroxide is preferably at least 2.0%. An example passivation agent is boric acid.
13) Japanese patent laying open no. H11-121419, to Hase et al., describes a composition having a basic pH, and being comprised of quaternary ammonium hydroxide, ozone and organic or inorganic acid. This application discloses that the preferable quaternary ammonium hydroxide is tetramethylammonium hydroxide (TMAH) and its concentration is at least 0.001 mol/l (7.4 wt %). In addition, this application discloses that an example inorganic acid is boric acid.
14) Finally, Japanese patent laying open no. H5-88377, to Sato et al., describes a developer composition having a basic pH, and being comprised of basic compound and organic or inorganic acid. This application discloses that an exemplary basic compound is tetramethylammonium hydroxide and an exemplary inorganic acid is boric acid. This application also discloses that the concentration of basic compounds is preferably at least 0.001 mol/l (7.4 wt % TMAH). Exemplary pHs are from 9.7 to 10.3.
Problems of the conventional fluorine compound or solvent containing cleaning compositions and the basic cleaning compositions and the method of manufacturing a semiconductor device using the same are now described below:
1) k-Value Shift and CD Loss
Recently, ultra low-k (ULK, k value<2.4) and extreme low-k (ELK, k-value<2.2) dielectric have been adopted in a 65 nanometers or less technology node. Plasma-etch processes, which have been widely used for construction of dual damascene structures, damage low-k dielectric, especially porous low-k dielectric. The conventional fluorine-based compositions or solvent containing cleaning compositions and the acidic (pH<4) or basic (pH>7) compositions increase the k-value of ULK or ELK dielectrics and cause CD loss.
2) Corrosion of Copper Surface
Copper surface control is considered to be important for reliable electrical properties. The conventional compositions containing a fluorine compound or a solvent and the conventional acidic (pH<4) or basic (pH>7) compositions corrode copper surfaces.